option

Documentation

Overview

Package option provides a way to represent optional values. It basically is a struct with a pointer to the value, but with a lot of little helper methods. It supports JSON marshaling and unmarshaling.

Index

• type Option
  • func None[T any]() Option[T]
  • func Some[T any](value T) Option[T]
  • func TupleToOption[T any](value T, ok bool) Option[T]
  • func (option *Option[T]) Apply(f func(T) T)
  • func (option Option[T]) GetValue() (T, bool)
  • func (option Option[T]) IsAbsent() bool
  • func (option Option[T]) IsPresent() bool
  • func (option Option[T]) MarshalJSON() ([]byte, error)
  • func (option Option[T]) MustValue() T
  • func (t *Option[T]) Scan(v interface{}) error
  • func (option Option[T]) String() string
  • func (option *Option[T]) UnmarshalJSON(data []byte) error
  • func (option *Option[T]) Update(value T)
  • func (t Option[T]) Value() (driver.Value, error)
  • func (option Option[T]) ValueOrDefault(fallback T) T

Types

type Option

type Option[T any] struct {
	// contains filtered or unexported fields
}

Option is a container for an optional value of type T. It uses nil to represent the absence of a value.

func None

func None[T any]() Option[T]

None builds an Option when value is absent.

func Some

func Some[T any](value T) Option[T]

Some builds an Option when value is present.

func TupleToOption

func TupleToOption[T any](value T, ok bool) Option[T]

TupleToOption converts a tuple to an Option.

func (*Option[T]) Apply

func (option *Option[T]) Apply(f func(T) T)

Apply applies the given function to the value of the Option.

func (Option[T]) GetValue

func (option Option[T]) GetValue() (T, bool)

GetValue returns value and presence. If value is absent, returns zero value and false.

func (Option[T]) IsAbsent

func (option Option[T]) IsAbsent() bool

IsAbsent returns true when value is present.

func (Option[T]) IsPresent

func (option Option[T]) IsPresent() bool

IsPresent returns true when value is absent.

func (Option[T]) MarshalJSON

func (option Option[T]) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler.

func (Option[T]) MustValue

func (option Option[T]) MustValue() T

MustValue returns value if present or panics instead.

func (*Option[T]) Scan

func (t *Option[T]) Scan(v interface{}) error

Scan implements the sql.Scanner interface. It means that the Option can be scanned from a database value.

func (Option[T]) String

func (option Option[T]) String() string

String returns a string representation of the Option.

func (*Option[T]) UnmarshalJSON

func (option *Option[T]) UnmarshalJSON(data []byte) error

UnmarshalJSON implements json.Unmarshaler.

func (*Option[T]) Update

func (option *Option[T]) Update(value T)

Update updates the value of the Option.

func (Option[T]) Value

func (t Option[T]) Value() (driver.Value, error)

Value implements the driver.Valuer interface. To safely get the value of an Option, use GetValue().

func (Option[T]) ValueOrDefault

func (option Option[T]) ValueOrDefault(fallback T) T

ValueOrDefault returns value if present or the default value given instead.